Closure for containers



Dec. 17, 1957 c. H. PHILLIPS 2,816,687

CLOSURE FOR CONTAINERS Filed Sept. 14, 1954 l5 e 5 FIG. I

7 E 'IB FIG. 2

FIG. 3

'INVENTOR CLIFTON H. PHILLIPS HIS ATTORNEY United States Patent 1 2,816,687 CLOSURE FOR CONTAINERS Clifton H. Phillips, Demarest, N. J assignor to Shell Development Company, New York, N. Y., a corporation of Delaware Application September 14, 1954, Serial No. 456,003 1 Claim. (Cl. 220-85) This invention pertains to receptacles, such as metallic cans and drums, and has particularly to do with the arrangement of the discharge opening and the closure therefor. The invention includes several features, disclosed herein in combination, being respectively an improved construction of the discharge neck that surrounds the opening in the container wall, an improvement in the flange at the outer end of the neck whereby an externally threaded element such as a pump or faucet tube can be threadedly engaged thereto, and an improved cap suitable for retention by the neck and containing a dished diaphragm that provides a gas cushion between the cap wall and the diaphragm.

The present practice in providing outwardly projecting necks at discharge openings in walls of steel drums and cans, such as l-qt. and larger cans, is to attach to said wall at an opening therein a separately fabricated fitting that includes the neck and/ or to mount a threaded bushing Within a neck that is embossed in the container wall; this involves a special welding, soldering and/ or metal work ing operation, and is costly. it is often necessary to provide such necks with female threads for attachment of an externally threaded tubular element of a dispensing device. Such threads are usually formed in separate bushings of metal heavier than the neck wall, metal and/ or the neck is cylindrically tubular in shape and, hence, suitable for internal threading; such threads are not readily applied directly to necks made of light sheet metal, such as 1828 gauge metal which would be used if the neck were embossed from the container wall and of one piece therewith, particularly if the neck is not tubular but is of different diameters along its length to provide an abutment for retaining a cap.

Such female threads on the closure fittings were often used to retain externally threaded plug type closures. Press-snap caps, i. e., caps made of sprung metal having fingers that surround the neck and engage the under side of a rim or other abutment on the neck when pressed radially inwards and that release the abutment upon application of an inward pressure on the center of the cap, have the advantage of lightness, low cost, and the capability of rapid application and removal; they have, however, heretofore been used mainly on containers of small sizes, usually less than one gallon, because of the danger of leakage and/ or breathing, the former relating to the outward flow of fluid from the container upon a pressure rise and the latter to the inspiration of air upon a pressure drop. Such pressure changes occur commonly with changes in temperature but are more severe in larger containers that usually have more rigid walls that are less able to adapt themselves to changes in the volume of the larger quantities of liqiud stored. There is a further danger that the relatively larger amounts of liquid in large containers can apply a greater impact force against the cap when the container is inverted or dropped, leading to leakage and, in extreme cases, to dislodgement of the cap.

It is the general object of the invention to improve the closure arrangements on metal containers, said arrangements including necked outlets and female caps thereon, and to reduce the cost of such closure devices. Specific objects are: To reduce the cost of the container by forming the neck wholly integral with the container wall; to form the neck with an inturned flange, said flange being radial and circumferential cuts to define a plurality of.

so cut as to provide tabs that, when bent downward, provide inclined thread-like surfaces for receiving an externally threaded element of a dispensing device, whereby the neck may be made of light metal, e. g., embossed from the container wall; and to provide the cap with a cushion, specifically, with a diaphragm having a part dished away from the cap wall to form a gas cushion, whereby pressure within the container, such as caused by a rise in temperature or by the impact of the liquid contents of the con tainer against the diaphragm is less likely to destroy the sealing action of the diaphragm, whereby the said impact will be cushioned and its effect on the cap wall mitigated, and whereby the tendency of the inward displacement of the diaphragm due to suction within the container is reduced, so that light caps, including those of sprung metal, can be used on larger containers, including steel drums.

In summary, the improved cap, which may be of the press-snap type, and shaped to embrace the neck, carries a stiff, impervious diaphragm, e. g., made of a high modulus elastomer, preferably an elastomer such as polyethylene, polyvinyl chloride, the copolymer of polyvinylidine chloride with vinyl chloride, or other synthetic plastic, or vulcanized rubber, the marginal part of which engages the inner face of the cap wall so as to be sealingly pressed against the rim of the closure neck or the like by the cap wall, the central part of the diaphragm being dished away from the cap wall to provide an intervening gas cushion. The neck on the container is advantageously made of light-weight sheet metal, preferably embossed from the container wall itself, and to adapt it nevertheless to receive an externally threaded element, the neck has an inturned flange the inner edge of which is cut and bent so as to form an edge able to function as a screw thread. Thus, the edge may be cut at intervals to form a series of tabs that are integral with the flange and extend in a common circumferential direction, the tabs being bent down from their bases to provide thread-like inclined surfaces, the said flange having a continuous, annular sealing surface surrounding the said ring of tabs for engagement to the margin of the above-mentioned cap diaphragm.

The invention will be further described with reference to the accompanying drawing showing one preferred embodiment of the invention, wherein:

Figure 1 is a central sectional view through a closure according to the invention in assembled condition, a part only of the container being shown;

Figure 2 is an exploded view of the several elements constituting the closure;

Figure 3 is a plan view of the neck of the container, the cap being removed; and

Figure 4 is a fragmentary edge view of the flange, taken on the line 44 of Figure 3 but on an enlarged scale.

The container may be a steel drum that includes a side wall 5 and a fiat top or end wall 6 joined to the former at a chime 7, the walls being of light-weight steel, such as 8-25 gauge in the case of multi-gallon drums, or even thinner, to include about 29 gauge in the case of one or multi-quart cans. The top wall is embossed by suitable dies prior to assembly to the side wall to provide an integral neck 8, shown best in the lower part of Figure 2, the said neck being preferably shaped as a body of revolution and including a widened portion 9 to provide a downwardly directed annular abutment 10 that is spaced upwards from the wall 6 for engagement by the retaining elements of the cap, to be described. The neck further has at the upper extremity thereof an inwardly turned flange 11 the outer part of which is annularly continuous to provide a sealing face and the inner part of which is cut as shown in Figure 3 by a series of pairs of intersecting 3 tabs 12 that are integral at their bases to the flange and extend from their bases in a common circumferential direction. These tabs are bentdownward to make a small fingers 14 that form retaining means and extenddowu wards from the cap walla'bout 'theenlargement 9 and thence radially inward toengage the abutment10 .of. the neck. Downward pressure on the center of thewall 13 causes the fingers 14 to move radially outward,'-releasing themtrom the=neck and permitting .them to :clearmthe widened part 9; radially inwardly directed pressureagainst thefingers secures the cap to the neck. No-claim of novelty is made for the cap just described and other types of caps having means capable of engaging the abutment 10=may beemployed. The cap carries an impervious, i.-.e.,- leakproof and air-tight diaphragm 15, preferably made of reasonably stifi thin sheet material that is'reasonably stiff but yet flexible and has someelastic properties so astotorma sealwhenpressed against the flange 11, e. g., a high modulus elastomer, such as a-polyethylene or other plastic. material, .as indicated above, 'that is dished down at the center so as to provide a pocket. 16 between the diaphragm and the wall 13, the upper side of the diaphragm. margin being in engagementwith-the wall 13. The gas in the pocket 16 will, in most cases, be air, but maybe some other gas, e.v g., nitrogen. When the cap is attached to the neck-8 the lower side of the diaphragm margin is pressed in sealing relation against the flange 11 and particularly against the outer, continuous part thereof. A .cap seal or band 17 is applied over the cap and includes at least a peripheral part 18 that embraces the fingers 14 and so prevents their spreading to release the abutment 10 despite the application of an inward force against the-center of the cap.wall 13, either'deliberately or through suction within the-container. The band 17 may .also serve as a tamper-proof seal, applied by a special sealing tool and constructed to make'removal impossiblewithout deliberate destruction, whereby undetected tampering, pilferage or substitution of contents is improbable.

The band 17 may optionally extend over the entire top of the cap, as shown, being in that event advantageously made leakproof and airtight.

The gas iu the pocket 16 forms. acushion that absorbs the impact of the contents of the container against. the cap diaphragm when the container is dropped or inverted. ltfurther contributes to the tightness of the seal, makingthe closure tight against leakage at higher pressures than in the cape of caps with flat diaphragms. Thus, in one .actual test on. a cap of the type illustrated, 73-min. in diameter, it was found that the provision of the dished diaphragm increased the leakage pressure from about lbs. per sq. in. to 38 lbs. per sq. in. Without restriction toany theory, one possible explanation of the improved sealingaction may be stated: The efiectiveness of the seal between the diaphragm and the flange 11 depends upon the pressure with which the diaphragm is pressed down. With the usual fiat diaphragm the contents of the container tend to raise at least the lower surface of the diaphragm off the flange, the diaphragm being compressed against the cap wall, whereby a leakage passageway is developed at a moderately low pressure. However, with the dished diaphragm of the invention there is a body of gas in the pocket 16 above the diaphragm at a pressure substantially the same as that acting against the lower surface of the diaphragm, and this gas presses the margin of the diaphragm downward against the flange 11. Since the diaphragm is non-rigid, the pressure of the gas inthe pocket 16 rapidly assumes the pressure of the fluid acting againstthe lower side of the diaphragm, makingthe-im- 4 proved sealing action effective in cases of impact loads as well as steady pressure.

The dished diaphragm also improves the sealing action of the cap under conditions of partial vacuum, which tends toward inspiration of air; since the latter is usually moistthe stored product would thereby be contaminated.

The. elfect of the cap in reducing such entry of air may be explained as follows, again without restricting the disclosure -to the theory advanced: Regardless of the shape of the diaphragm, suction within the container suffic'ient to cause air seepage initially sets up a pressure diflerential across the diaphragm because such suction. draws the diaphragm downwards into tighter sealing relation. to theflange 11, whereby air is more likely to seep over the upper margin of the diaphragm than beneath it. This tends to draw the central part of thediaphragmdownwards. With a fiat diaphragm only asmall pressure differential sufiices to set up large tensile stresses in the.

diaphragm and cause some inward displacement of the marginal portion; such movement causes seepage of air also below the margin of the diaphragm. However, with the dished diaphragm of the invention far lower marginal stresses are set up, whereby the diaphragm does not move In an actual test with a until a far higher pressure. 73-mm. diameter cap of the type illustrated, which was applied to a 55-gallon steel drum, the drum was evacuated through a second opening to the extent that the drum was completely collapsed at a vacuum of 3.4 lbs.

per sq. in.; the cap maintained the vacuum, the pressures' after 24 and 48 hours being 3.3 and 3.1 lbs. per sq. in. subatmospheric, respectively. A similar cap with a fiatdiaphragm permitted air leakage into the drum already at subatmospheric pressures insufliciently low to cause visible deformation of the drum. Both these tests, as-

well as those described in the preceding paragraph, were performed on a neck having a flange 11 without the cuts and tabs 12.

It may be noted that the cuts in the flange 11 that form the tabs 12 further present irregularities that-aid in preventing radial movement of the diaphragm and, therefore, contribute to the tightness of the closure.

It may be further noted that the dished diaphragm inherently provides an ullage space within the container,

since if the container is improperly filled entirely to the flange 11 the diaphragm causes some excess liquid to overflow; this reduces the magnitude of pressure changesthat would otherwise result fromtemperature variations.

I claim as my invention:

A closure for 21 container having a top wall formedwith a discharge opening therein and having a neck carried by the wallsurrounding said discharge opening come-- prising: acontinuous, impervious, centrally downwardly permanently dished flexible diaphragm overlying saidneck and.x.covering the opening said diaphragm being of uniform thickness throughout, a cap engaging themargin of the diaphragm to press the latter against the fiat serrated. top :of the neck in sealing relation and having-dependent locking fingers adapted to engage a portion-of the neck, the central portion of said diaphragm being spaced fromsaidtcapto provide an intervening gas cushion.

References Cited in the file of this patent UNITED STATES PATENTS 225,752 Griswold et a1 Mar. 23, 1880 1,722,256 Wikstrom July 23, 1929 1,739,759 Hothersall Dec. 17, 1929 1,788,282 Drager Ian. 6, 1931 2,121,843 Vaughn June 28, 1938 2,460,720 Thompson Feb. 1, 1949- 2,681,742 Miller June 22, 1954 2,751,073 Sheeran June 1-9, 1-956- FORE-IGN PATENTS 1,015,071 France June 25, 1952' 

